Climate Change: Crocodilians Were Forced To Relocate Due To Cooling Temperatures

A sudden cold spell paired with changing sea levels could have caused the retreat of crocodiles over millions of years.

Crocodilians rely on external heat sources, such as the sun, for body heat, so climate changes can have a significant impact. To find just what kind of impact climate change had on ancient crocs, Researchers from Imperial College London, the University of Oxford, the Smithsonian Institution, and the University of Birmingham compiled a complete crocodilian history.

They found that at higher latitudes of modern-day Europe and America, declining temperatures had a major impact on crocodilians and their relatives. While at lower latitudes, crocodilians suffered from increasingly arid climates turning their wetlands into vast deserts and erected mountain ranges.

"Crocodilians are known by some as living fossils because they've been around since the time of the dinosaurs. Millions of years ago these creatures and their now extinct relatives thrived in a range of environments that ranged from the tropics, to northern latitudes and even deep in the ocean," Dr. Philip Mannion, joint lead author from the Department of Earth Science and Engineering at Imperial College London, explained. "However, all this changed because of changes in the climate, and crocodilians retreated to the warmer parts of the world. While they have a fearsome reputation, these creatures are vulnerable and looking back in time we've been able to determine what environmental factors had the greatest impact on them. This may help us to determine how they will cope with future changes."

Ancient crocodilians that inhabited the ocean weren't safe from climate change either. When sea levels were higher, the continental shelf was longer and provided ample feeding grounds for these marine reptiles. However, when sea levels dropped, crocodilians suffered.  

Crocodilians include modern crocodiles, alligators, caimans and gavials and their extinct ancestors. Crocodilians first appeared in the Late Cretaceous period, approximately 85 million years ago, and since then have undergone a very diverse evolution. Of the 23 species that exist today, six are considered endangered or vulnerable, according to a news release. 

This study provides clues as to how modern crocodilians may react to future climate change. According to the researchers warming temperatures may even allow the species to re-diversify.

Their findings were recently published in the journal Nature Communications.

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